Slow closing throttle check



United States Patent O SLOW CLOSING THROTTLE CHECK Leland l5. Read, Normandy, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application December 3, 1951, Serial No. 259,609

1l) Claims. (Cl. 261-34) i This invention relates to carburetors for internal combustion engines, and resides particularly in novel means for retarding the iinal portion of the throttle closing movement in order to prevent stalling of the engine in case the throttle pedal is suddenly released, especially subsequent' to a sudden opening of the throttle. The use of such a device is found particularly suitable for engines equipped with torque converters of the hydraulic type, althoughV advantages can be obtained in engine operation regardless of the type of transmission of power from the engine to the wheels of the vehicle. Dash pot arrangements have been provided for accomplishing the above function, but these have been relatively complicated and expensive in construction. n

In the particular construction of the present invention, the dash pot arrangement is usually die-cast integral with the carburetor structure in a position to receive gasoline and be substantially flooded. Instead of the usual piston arrangement, a diaphragm and displacement member are provided in the dash pot, with the diaphragm sealing the dash pot against leakage of fuel pressure except through metered orifices above the displacement member. A presser foot of suitable dimensions is arranged to engage the diaphragm on closing movement of the throttle and move the displacement member in a direction to compress the fuel in the dash pot cylinder.v The rate of throttle closing is therefore determined by leakage of the fuel past the displacement member, and also through a metered orifice. The displacement member used is inexpensive, since a ball of standard dimensions is regarded as suitable, not only to act as a piston or displacement member, but also to provide a weight whose inertia will oppose lthe sudden application of force applied during throttle closing.

It is one of the objects of the present invention to provide a novel, simplified, and less expensive dash pot t'o control the closing movement of the throttle of a carburetor. z

It is also an object of the invention to provide in a device of this character a structure which williexclude the entrapment of vapors from affecting the action of the device. l

Other objects of the invention will become apparent as the description proceeds.

In the drawings,

Fig. l is a side elevation of a carburetor partly section. n l

Fig. 2 is an enlarged view in section of the dash-pot device according to this invention.

Fig. 3 is a view illustrating the position of the parts with the throttle open.

In Fig. l is shown a downdraft carburetor of known construction, having a mixing tube 8 formed integral with a fuel bowl 9, within which fuel is maintained at a substantially constant level by means of the usual needle valve and float mechanism (not shown).` In thelower part of the mixture tube is mounted a butterfly throttle 2,713,999" Patented July 26, 1955 ice y valve 10 on a rotatable shaft 11, to one end of which is rigidly attached an arm 12.

In the lower part of the iloat bowl there is formed an auxiliary pump pressure chamber 13 having a top wall 14 with an inlet aperture 15. A exible diaphragm 16 extends across the pressure chamber and has an actuating stem 17 secured centrally thereof and protruding upwardly through the wall 14 and within a guide tube 18. A collar 19 seats against the annular shoulder 20 on the actuating stem and, in turn, forms a seat for a coil compression spring 21 constantly urging the stem 17 and the pump diaphragm upwardly in a direction to displace the fuel within the chamber 13 through a suitable passage into the mixture tube. Below the pump diaphragm is a chamber 22 connected by a suction passage 23 to the mixing tube posterior of the throttle valve 10.

A gooseneck type of link 25 extends upwardly from the vicinity of the throttle valve, and is connected therewith by a small link 26 by way of throttle shaft arm 12. The later-al extension 27 from the gooseneck link has an opening 28, which slidably receives the pump stem 17. The carburetor is also provided with a metering rod 29, which, at its lower extremity projects into a main metering orifice element 30. Its upper end is carried by a bracket element 31 having extension 32 normally secured between a shoulder on the stem 17 and a coil spring 33 mounted on the reduced upper extension 34 of the pump stem and maintained there by a suitable retainer.

Under normal operating conditions, pump diaphragm 16 follows the movement of the throttle valve drawing fuel from the bowl by way of port 15 as the throttle is closed, and expelling this fuel through an outlet passage (not shown) into the mixture tube as the throttle valve is opened. The pump diaphragm may also move upwardly a slight distance independently of the throttle connection when suction drops in the mixture barrel posterior to the throttle. This pump is more fully described and claimed in an accompanying application, Serial No. 117,772, liled September 26, 1949, in the name of John S. Carrey, now Patent 2,619,333 issued November Within the fuel bowl 9 is a dash pot cylinder 36 formed `as an integral part with the top wall 14 of the pump pressure chamber and immediately adjacent the tubular guide 18 for stem 17. At its lower end a small passage 37 conp nects with the interior of the dash pot and opens to the fuel bowl, and is provided with a ball check valve 38 on a 'seat formed at the inner end of the passage. Within the dash pot is a metal ball 39, or the like, forming a piston for the dash pot. Ball 39 works in this cylinder, and is constantly urged upwardly by a coil compression spring 40 between the ball and the lower inner wall of the dash pot. The upper end of the dash pot is closed by a exible diaphragm secured in place over the open end by a spring ring 44, or the like, seating beneath the shoulders 46 staked over at spaced points to maintain the ring and diaphragm in a recess in the cylinder wall. Located above the maximum diameter of the ball 39, when in its upper position as shown in Fig. 3, is a metered port 49 opening from the interior of the dash pot to the fuel bowl 9.

The lateral extension 27 of the gooseneck link 25 has a depending clement 50 inalignment with the dash pot provided at its lower end with a presser foot 51 which is formed in this particular case by a right-angular extension from the depending portion 59. The area of thisv particular presser foot 51 is important to the action of the device as a means for retarding throttle closing. On the one hand, the presser foot cannot be the full Y width of the dash pot internal diameter, but, on the other hand, it must be large enough to prevent pockets being formed in the diaphragm when the presser foot is in its lowermost position as shown in Fig. l.

The position of the ball, diaphragm, and presser foot for throttle-closed positions is illustrated in Fig. l. Referring to Fig. 3, however, it will be seen that, in a throttle open position, the presser foot 51 is `raised from engagement with the diaphragm and ball. In this position, all of the vapors and air which mi'ght be present under the diaphragm are forced out through the small metering passage 49, since the ball 39 acts as a displacement member completely filling the cavity beneath the diaphragm. In the raised position, the piston-like action of the ball 39 will cause the check valve 38 to permit the complete filling of the dash pot from the fluid in the fuel bowl 9. Fig. 2 illustrates the position of the parts within the dash pot in the raised position, and it can be readily seen from this ligure that the amount of clearance between the upper part of the ball, the diaphragm, and the walls of the dash pot cylinder, is at a minimum, thus eliminating any cushioning of the action of the dash pot from the presence of gas or air when the diaphragm is pressed downwardly by the presser foot 51 during throttle closing movement.

In operation, it can be seen that, as the throttle is moved from the position shown in Fig. l to the position shown in Fig. 3, the dash pot will be completely filled with fluid from the bottom of the fuel bowl 9, and the action of the ball and diaphragm will be such as to exclude any entrapment of vapors or gas to impair the subsequent action of the dash pot to resist closing movement of the throttle. If, from the position shown in Fig. 3, the throttle is now suddenly closed, the presser foot 51 will engage the diaphragm 45 compressing the diaphragm and forcing the ball 39 downwardly against an entrapped column of fluid within the dash pot. The rate of nal closing of the throttle will therefore depend upon the rate of leakage of the fuel past the ball 39, and out of the metered orifice 49. Both of these means will determine the rate of throttle closing, since, when l the liquid escapes around the sides of the ball, it will exert a pressure against the underside of the diaphragm until such time as it can escape through the metered orifice 49. By this arrangement, a structure has been provided which has a double action resisting the closing movement of the throttle, and, even if the piston which comprises the ball 39, or its cylinder wall, should wear, the pressure of fuel acting against the diaphragm after it escapes past the ball forms an added assurance that the closing action of the throttle will be retarded.

It will be apparent from the above description that a device has been described which Will fulfill all of the objects of the invention set forth above. It will be obvious to those skilled in the art that various modifications may be made in the described structure without departing from the spirit of the invention. For this reason, the above described device is for the purpose of illustration of a preferred manner of applying the invention, and should not be regarded in a limiting sense.

I claim:

l. ln a carburetor, a mixing tube, a throttle valve in said tube, a fuel bowl for supplying fuel to said mixing tube, a linkage operatively connected with said throttle, a dash pot receiving fuel from said bowl through an inlet and having a metering discharge passage, flexible fluid-tight means for said dash pot, means on saidl throttle linkage for deforming said flexible means during throttle closing action, means for restricting reverse flow through said inlet, and means co-acting with said flexible means for displacing gases and air trapped in said dash pot through said discharge passage.

2. In a carburetor, a mixing tube, a throttle valve in said tube, a fuel bowl for supplying fuel to said mixing tube, a linkage operatively connected with said throttle, a dash pot receiving fuel from said bowl through an inlet and having a metering discharge passage, flexible fluid-tight means for said dash pot, means on said throttle linkage for deforming said flexible means iu throttleclosed positions, means for restricting reverse flow through said inlet, and means within the dash pot forming a second metering means for resisting throttle closing movement.

3. In a carburetor, a mixing tube, a throttle valve in said tube, a fuel bowl for supplying fuel to said mixing tube, a linkage operatively connected with said throttle, a dash pot receiving fuel from said bowl through an inlet and having a metering discharge passage, flexible fluid-tight means for said dash pot, means on said throttle linkage for deforming said flexible means in throttleclosed positions, means for restricting reverse flow through said inlet, and means within the dash pot coacting with said flexible means for positively expelling vapors and gases from beneath said fluid-tight means.

4. In a carburetor, a mixing tube, a throttle valve in said tube, a constant level fuel chamber'for supplying fuel to said mixing tube, linkage for actuating said throttle, a dash pot in said fuel chamber for receiving fuel therefrom through an inlet and provided with a metering discharge orifice, flexible fluid-tight means for said dash pot, means on said throttle linkage for deforming a substantial portion of the outer surface of the exible means during throttle closing action of said linkage, means for restricting reverse flow through said inlet, and means within the dash pot for displacing the fuel duringv throttle closing movement, and contoured to co-aet with said flexible means and expel the vapors and gases from beneath the flexible diaphragm in throttleopen positions.

5. In a carburetor, a mixing tube, throttle actuating means for controlling a throttle valve in said tube, a constant levelv fuel chamber for supplying fuel to said tube, and means for retarding the closing movement of the throttle'and its linkage, comprising an open top, fluidtight chamber having an inlet communicating with said constant level chamber, a flexible diaphragm closing the upper end of said chamber, a displacement member constantly urgedin a direction to expand said diaphragm in an outward direction to thereby expel'trapped gases orl vapors from beneath the diaphragm, a metering orifice located in the -wallof said chamber, generally above the -displacement member when in its raised position, means for restricting reverse flow through said inlet, and means on said throttle linkage engaging said diaphragm during throttle-closing movement.-

6. In a carburetor, a mixing tube, a linkage for actuating a throttle valve inside the tube, a constant level fuel chamber for supplying fuel to said mixing tube, a means for retarding the closing action of said throttle linkage, comprising an open top cylinder, means for charging .said cylinder with .fuel from the constant level chamber, a discharge orifice from said cylinder, and

means for controlling the rate of flow through said discharge orifice, including a diaphragm for the upper open endv of saidcylinder and a fluid displacement member beneath said diaphragm, means for urging said displacement member into contact with the diaphragm for displacing trapped vaporsv or gases, means for restricting reverse flow through said means for charging said cylinder, and means on said linkage engaging said diaphragm and actuating said displacement member during throttleclosing movement.

7. In a carburetor, a mixing tube, a linkage for actuating a throttle valve inside the tube,V a constant level fuel chamber for supplying fuel to said mixing tube, a means for retarding the closing action of Vsaid throttle linkage, comprising an open top cylinder, means for charging said cylinder with fuel from the constant level chamber, a fluid-tight seal for the open end of said cylinder, a fluid displacement member in said cylinder, a vent passage between said seal and said member, spring means urging said member ltoward said seal, means for restricting reverse ow through said means for charging said cylinder and means on said linkage actuating said displacement member during throttle closing movement.

8. In a carburetor, a mixing tube, a throttle valve in said tube, a fuel bowl for supplying fuel to said mixing tube, a pump receiving fuel from said bowl, a linkage operatively connecting said throttle and said pump, a dash pot integral with said pump, receiving fuel from said bowl through an inlet and having a metering discharge passage, flexible fluid-tight means on said dash pot above said discharge passage, means on said throttle linkage for deforming said flexible means during throttleclosing action, means for restricting reverse ow through said inlet, and a piston for said dash pot below said discharge passage.

9. In a carburetor, a mixing tube, a throttle valve in said tube, a fuel bowl for supplying fuel to said mixing tube, a pump receiving fue] from the said bowl, a linkage operatively connecting said throttle and said pump, a dash pot integral with said pump receiving fuel through an inlet from said bowl and having a metering discharge passage, flexible duid-tight means above said discharge passage, means on said throtlte linkage for deforming said ilexible means in throttle-closed positions, means for restricting reverse ow through said inlet and means within the dash pot below said discharge passage for expelling vapors and gases from beneath said uid-tight means.

10. In a carburetor, a mixing tube, a throttle valve in said tube, a fuel bowl for supplying fuel to said mixing tube, a pump having a casing receiving fuel from the said bowl, a linkage operatively connecting said throttle and said pump, a dash pot integral with said casing receiving fuel through an inlet in said casing from said bowl and having a metering discharge passage, flexible uid-tight means above said discharge passage, means on said throttle linkage for deforming said flexible means in throttle-closed positions, means for restricting reverse ow through said inlet and means within the dash pot below said discharge passage for expelling vapors and gases from beneath said fluid-tight means.

References Cited in the file of this patent UNITED STATES PATENTS Sinclair Apr. 26, 1938 2,144,153 Henning Jan. 17, 1939 2,592,513 Haeusler Apr. 8, 1952 

